The effects of acidosis on chronically hypoxic neurons in culture

Neuropathologic changes associated with perinatal hypoxic-ischemic events in the human infant most often result from chronic hypoxia rather than from acute asphyxia. To characterize the effects of acidosis associated with chronic hypoxia in developing neurons, cerebral cortical cultures obtained from fetal mice were exposed to 5% O2 continuously for either 24 or 48 h at 10 days after plating. At the conclusion of the hypoxic insult (HI), neuronal morphology was relatively intact for both conditions even though culture medium reflected significant reductions in pH and bicarbonate with elevation of lactate; cultures exposed to the longer HI manifested statistically greater aberrations from control values. Total benzodiazepine (BDZ) binding and clonazepam (CLO)-displaceable BDZ binding, reflecting the neuronal component of the receptor, were only modestly reduced immediately after HI, but were thereafter significantly and progressively lower over the 72 h normoxic recovery period. Although neuronal integrity was progressively diminished with both insults, morphology was always more normal and CLO higher in cultures subjected to 48-h HI compared to the 24-h HI (34.0 +/- 9.8 vs 1.8 +/- 1.1% of control values at 72 h, respectively; P less than 0.001). In contrast, values obtained for the glial marker Ro5-4864-displaceable BDZ binding were higher than control values for both conditions. Outcome was not influenced by removal of acidotic medium, nor by normalization of lactate. These data suggest that, with time, neurons in vitro adapt to severe hypoxia and that alterations in pH, lactate, and bicarbonate by themselves are probably not neurotoxic since the most acidotic cultures exhibited improved survival.     

The role of dendritic cells in the induction and regulation of immunity to microbial infection.

Dendritic cells (DCs) play a critical role in the initiation and regulation of immune responses. Recent advances have begun to uncover the nature and diversity of DC-pathogen interactions and the modulation of DC function by microbial stimuli. Antigen pulsed DCs have also been shown in several infection models to induce high levels of protective immunity and to display immunotherapeutic potential. The study of the function of DCs in the response to infection is thus an exciting and rapidly expanding field with important implications for both fundamental and clinical immunology.     

Increased capillary permeability in rat brain induced by factors secreted by cultured C6 glioma cells: role in peritumoral brain edema

Summary To investigate whether brain tumors secrete a factor(s) responsible for peritumoral brain edema, we studied the effect of conditioned medium from cultured C₆ glioma cells on rat brain capillary permeability. Three different fractions of conditioned medium were obtained. SUP-N was a culture supernatant incubated 4 hours in serum-free medium. SUP-C was the 60–100 fold concentrated fraction obtained by dialysis-concentration of SUP-N; it contained 950 µ g/ml of protein > 10 k-daltons from 3 × 10⁸ cells. SUP-L was a water-dispersible lipid fraction from SUP-N; the major components of SUP-L were neutral lipids and free fatty acids. The supernatant fractions and their corresponding control solutions were infused into normal rat brain, and capillary permeability was determined using quantitative autoradiography by measuring the unidirectional entry constant, K (µ 1/g · min), of ¹⁴C-alpha-aminoisobutyric acid (¹⁴C-AlB) into brain tissue. SUP-C and SUP-L significantly increased capillary permeability of normal brain; the effect of SUP-C was more intense and extensive than that of SUP-L. The highest mean K value (K_max) of SUP-C was 10.83 ± 0.99 and that of the control was 2.53 ± 0.22 (p < 0.001). The Km. of SUP-L was 5.61 ± 0.23 and that of the control was 2.67 ± 0.36 (p < 0.01). A time-course study after infusion of SUP-C demonstrated that more than 1.5 hours is required for the supernatant fraction to open the barrier and that the effect of SUP-C was reversible. The increase of capillary permeability induced by SUP-C was significantly inhibited by pretreatment of rats with dexamethasone (10 mg/kg, ip) 1 hour before intracerebral infusion of SUP-C (K_max (untreated): 8.30 ± 0.82, K_max (treated): 1.33 ± 0.64, p < 0.001). These results indicate that experimental brain tumors secrete at least two different diffusible factors responsible for capillary endothelial leakage in normal brain. One is a protein of molecular weight greater than 10 k-daltons, whose effect is inhibited by glucocorticoids, and the other is a waterdispersible lipid.Presented in part at the meeting of the American Association for Cancer Research, Atlanta, GA, May 1987.     

Bilateral congenital cholesteatoma: a cause or result of chronic otitis media with effusion?

Bilateral congenital cholesteatoma in children is unusual, and our experience with a case arising in a 6-year-old boy is described. Various theories of the origin of this disease are briefly reviewed. The possibility that this entity may be more common than previously realized, and its relationship to eustachian tube obstruction and middle ear effusions, are also discussed.     

Acquisition of murine major histocompatibility complex gene products by schistosomula of Schistosoma mansoni

Schistosoma mansoni schistosomula recovered from the lungs of inbred mice were shown to possess serologically detectable alloantigens on their tegumental surfaces. Using appropriate antisera and infected congenic and recombinant mice as worm donors, gene products of the K and I subregions of the major histocompatibility complex were demonstrated among these alloantigens acquired by the parasites. In contrast, other cell surface alloantigens, such as Thy 1, Ly 1, and H-Y and the serum proteins albumin, C3 and Ig, could not be detected on the surface of lung schistosomula by means of comparable techniques. In another series of experiments, schistosomula recovered from the lungs of mice and reinjected into allogeneic recipients were shown to exchange their alloantigens during an 87-h period of examination. Similarly, lung schistosomula cocultured with allogeneic lymphocytes were shown to acquire major histocompatibility complex (MHC) coded antigens from the cells. It is possible that as acquired host molecules, MHC gene products may disguise the surface of schistosome parasites thereby rendering them insusceptible to immune attack.     

A randomized controlled trial comparing the frequency of acute reactions to plasma-removed platelets and prestorage WBC-reduced platelets

BACKGROUND: Removal of the plasma supernatant from platelets before transfusion is effective in preventing acute reactions to platelets caused by cytokines. Prestorage WBC reduction of platelets may be even more effective at preventing reactions as the WBCs are removed and WBC-derived cytokines do not accumulate in this component. This study evaluates the effectiveness of plasma removal and two methods of prestorage WBC reduction for preventing acute reactions to platelets. STUDY DESIGN AND METHODS: Platelets given to adults with hematologic malignancies were randomly allocated to one of three types: plasma supernatant removed and a platelet storage solution added, whole blood-derived platelets that are prestorage WBC reduced by filtration before storage, and prestorage WBC-reduced apheresis platelets. Patients were monitored before, during, and after transfusion, and the severity of reactions was graded on a Likert scale. RESULTS: A total of 129 patients from four centers were given 1190 platelet transfusions. The overall frequency of reactions was 13.6 percent (162 of 1190), 21.3 percent (36 of 169) for the plasma-removed platelets, 11.4 percent (59 of 517) for random donor WBC-reduced platelets, and 13.3 percent (67 of 504) for apheresis WBC-reduced platelets (p=0.384). The overall frequency of severe reactions was 4.1 percent with plasma-removed platelets, 1.7 percent for whole blood-derived, prestorage WBC-reduced platelets, and 1.4 percent for prestorage WBC-reduced apheresis platelets. CONCLUSION: The frequency of reactions to plasma-removed platelets and prestorage WBC-reduced platelets was not significantly different; however, the power of the study for this comparison was low. There was no difference in the frequency of reactions to the two types of prestorage WBC-reduced platelets. The frequency of severe reactions to prestorage WBC-reduced platelets is low, occurring in only 1 to 2 percent of transfusions.     

TLR9 regulates Th1 responses and cooperates with TLR2 in mediating optimal resistance to Mycobacterium tuberculosis

To investigate the role of Toll-like receptor (TLR)9 in the immune response to mycobacteria as well as its cooperation with TLR2, a receptor known to be triggered by several major mycobacterial ligands, we analyzed the resistance of TLR9(-/-) as well as TLR2/9 double knockout mice to aerosol infection with Mycobacterium tuberculosis. Infected TLR9(-/-) but not TLR2(-/-) mice displayed defective mycobacteria-induced interleukin (IL)-12p40 and interferon (IFN)-gamma responses in vivo, but in common with TLR2(-/-) animals, the TLR9(-/-) mice exhibited only minor reductions in acute resistance to low dose pathogen challenge. When compared with either of the single TLR-deficient animals, TLR2/9(-/-) mice displayed markedly enhanced susceptibility to infection in association with combined defects in proinflammatory cytokine production in vitro, IFN-gamma recall responses ex vivo, and altered pulmonary pathology. Cooperation between TLR9 and TLR2 was also evident at the level of the in vitro response to live M. tuberculosis, where dendritic cells and macrophages from TLR2/9(-/-) mice exhibited a greater defect in IL-12 response than the equivalent cell populations from single TLR9-deficient animals. These findings reveal a previously unappreciated role for TLR9 in the host response to M. tuberculosis and illustrate TLR collaboration in host resistance to a major human pathogen.     

Insuficiência hepática fulminante após transplante simultâneo de rim‐pâncreas: um relato de caso

We describe an unusual case of hyperacute hepatic failure following general anesthesia in a patient receiving a simultaneous kidney‐pancreas transplant. Despite an aggressive evaluation of structural, immunological, viral, and toxicological causes, a definitive cause could not be elucidated. The patient required a liver transplant and suffered a protracted hospital course. We discuss the potential causes of fulminant hepatic failure and the perioperative anesthesia management of her subsequent liver transplantation.